Revert "wip"

This reverts commit ca49fd402af8e7bf613c43e996274b5a017958d2.

15 files changed, 62 insertions, 29 deletions

diff --git a/src/rustc/metadata/encoder.rs b/src/rustc/metadata/encoder.rs
index 47d91c10818..87ef3b4749c 100644
--- a/src/rustc/metadata/encoder.rs
+++ b/src/rustc/metadata/encoder.rs
@@ -116,7 +116,7 @@ fn encode_mutability(ebml_w: ebml::Writer, mt: class_mutability) {
 type entry<T> = {val: T, pos: uint};
 
 fn add_to_index(ecx: @encode_ctxt, ebml_w: ebml::Writer, path: &[ident],
-                index: &mut ~[entry<~str>], name: ident) {
+                &index: ~[entry<~str>], name: ident) {
     let mut full_path = ~[];
     full_path.push_all(path);
     full_path.push(name);
diff --git a/src/rustc/metadata/tydecode.rs b/src/rustc/metadata/tydecode.rs
index 1375ff2d0be..f3fa0e3f350 100644
--- a/src/rustc/metadata/tydecode.rs
+++ b/src/rustc/metadata/tydecode.rs
@@ -394,6 +394,7 @@ fn parse_arg(st: @pstate, conv: conv_did) -> ty::arg {
 
 fn parse_mode(st: @pstate) -> ast::mode {
     let m = ast::expl(match next(st) {
+        '&' => ast::by_mutbl_ref,
         '-' => ast::by_move,
         '+' => ast::by_copy,
         '=' => ast::by_ref,
diff --git a/src/rustc/metadata/tyencode.rs b/src/rustc/metadata/tyencode.rs
index 83f92b44fe8..88d83ca23f4 100644
--- a/src/rustc/metadata/tyencode.rs
+++ b/src/rustc/metadata/tyencode.rs
@@ -332,6 +332,7 @@ fn enc_arg(w: io::Writer, cx: @ctxt, arg: ty::arg) {
 
 fn enc_mode(w: io::Writer, cx: @ctxt, m: mode) {
     match ty::resolved_mode(cx.tcx, m) {
+      by_mutbl_ref => w.write_char('&'),
       by_move => w.write_char('-'),
       by_copy => w.write_char('+'),
       by_ref => w.write_char('='),
diff --git a/src/rustc/middle/borrowck.rs b/src/rustc/middle/borrowck.rs
index e2f7ba20642..414890cbd7c 100644
--- a/src/rustc/middle/borrowck.rs
+++ b/src/rustc/middle/borrowck.rs
@@ -396,10 +396,10 @@ type req_maps = {
     pure_map: HashMap<ast::node_id, bckerr>
 };
 
-fn save_and_restore<T:Copy,U>(save_and_restore_t: &mut T, f: fn() -> U) -> U {
-    let old_save_and_restore_t = *save_and_restore_t;
+fn save_and_restore<T:Copy,U>(&save_and_restore_t: T, f: fn() -> U) -> U {
+    let old_save_and_restore_t = save_and_restore_t;
     let u <- f();
-    *save_and_restore_t = old_save_and_restore_t;
+    save_and_restore_t = old_save_and_restore_t;
     move u
 }
 
diff --git a/src/rustc/middle/borrowck/check_loans.rs b/src/rustc/middle/borrowck/check_loans.rs
index 51beff021fa..0c79c0fcd7f 100644
--- a/src/rustc/middle/borrowck/check_loans.rs
+++ b/src/rustc/middle/borrowck/check_loans.rs
@@ -529,7 +529,8 @@ impl check_loan_ctxt {
                 ast::by_move => {
                     self.check_move_out(*arg);
                 }
-                ast::by_ref | ast::by_copy | ast::by_val => {
+                ast::by_mutbl_ref | ast::by_ref |
+                ast::by_copy | ast::by_val => {
                 }
             }
         }
@@ -541,9 +542,9 @@ fn check_loans_in_fn(fk: visit::fn_kind, decl: ast::fn_decl, body: ast::blk,
                      visitor: visit::vt<check_loan_ctxt>) {
 
     debug!("purity on entry=%?", copy self.declared_purity);
-    do save_and_restore(&mut(self.in_ctor)) {
-        do save_and_restore(&mut(self.declared_purity)) {
-            do save_and_restore(&mut(self.fn_args)) {
+    do save_and_restore(self.in_ctor) {
+        do save_and_restore(self.declared_purity) {
+            do save_and_restore(self.fn_args) {
                 let is_stack_closure = self.is_stack_closure(id);
                 let fty = ty::node_id_to_type(self.tcx(), id);
                 self.declared_purity = ty::determine_inherited_purity(
@@ -666,7 +667,7 @@ fn check_loans_in_expr(expr: @ast::expr,
 fn check_loans_in_block(blk: ast::blk,
                         &&self: check_loan_ctxt,
                         vt: visit::vt<check_loan_ctxt>) {
-    do save_and_restore(&mut(self.declared_purity)) {
+    do save_and_restore(self.declared_purity) {
         self.check_for_conflicting_loans(blk.node.id);
 
         match blk.node.rules {
diff --git a/src/rustc/middle/borrowck/gather_loans.rs b/src/rustc/middle/borrowck/gather_loans.rs
index 5dfde8c9af6..327db51518b 100644
--- a/src/rustc/middle/borrowck/gather_loans.rs
+++ b/src/rustc/middle/borrowck/gather_loans.rs
@@ -115,6 +115,10 @@ fn req_loans_in_expr(ex: @ast::expr,
         let scope_r = ty::re_scope(ex.id);
         for vec::each2(args, arg_tys) |arg, arg_ty| {
             match ty::resolved_mode(self.tcx(), arg_ty.mode) {
+              ast::by_mutbl_ref => {
+                let arg_cmt = self.bccx.cat_expr(*arg);
+                self.guarantee_valid(arg_cmt, m_mutbl, scope_r);
+              }
               ast::by_ref => {
                 let arg_cmt = self.bccx.cat_expr(*arg);
                 self.guarantee_valid(arg_cmt, m_imm,  scope_r);
diff --git a/src/rustc/middle/kind.rs b/src/rustc/middle/kind.rs
index 1da145cabc9..9aff382775c 100644
--- a/src/rustc/middle/kind.rs
+++ b/src/rustc/middle/kind.rs
@@ -319,13 +319,13 @@ fn check_expr(e: @expr, cx: ctx, v: visit::vt<ctx>) {
         for exprs.each |expr| { maybe_copy(cx, *expr, None); }
       }
       expr_call(f, args, _) => {
-        let mut i = 0;
+        let mut i = 0u;
         for ty::ty_fn_args(ty::expr_ty(cx.tcx, f)).each |arg_t| {
             match ty::arg_mode(cx.tcx, *arg_t) {
               by_copy => maybe_copy(cx, args[i], None),
-              by_ref | by_val | by_move => ()
+              by_ref | by_val | by_mutbl_ref | by_move => ()
             }
-            i += 1;
+            i += 1u;
         }
       }
       expr_field(lhs, _, _) => {
@@ -335,7 +335,7 @@ fn check_expr(e: @expr, cx: ctx, v: visit::vt<ctx>) {
             Some(ref mme) => {
                 match ty::arg_mode(cx.tcx, mme.self_arg) {
                     by_copy => maybe_copy(cx, lhs, None),
-                    by_ref | by_val | by_move => ()
+                    by_ref | by_val | by_mutbl_ref | by_move => ()
                 }
             }
             _ => ()
@@ -465,10 +465,18 @@ fn check_imm_free_var(cx: ctx, def: def, sp: span) {
             cx.tcx.sess.span_err(sp, msg);
         }
       }
+      def_arg(_, mode) => {
+        match ty::resolved_mode(cx.tcx, mode) {
+          by_ref | by_val | by_move | by_copy => { /* ok */ }
+          by_mutbl_ref => {
+            cx.tcx.sess.span_err(sp, msg);
+          }
+        }
+      }
       def_upvar(_, def1, _, _) => {
         check_imm_free_var(cx, *def1, sp);
       }
-      def_arg(*) | def_binding(*) | def_self(*) => { /*ok*/ }
+      def_binding(*) | def_self(*) => { /*ok*/ }
       _ => {
         cx.tcx.sess.span_bug(
             sp,
diff --git a/src/rustc/middle/liveness.rs b/src/rustc/middle/liveness.rs
index bdf808e8568..69b325b03a4 100644
--- a/src/rustc/middle/liveness.rs
+++ b/src/rustc/middle/liveness.rs
@@ -398,8 +398,8 @@ impl IrMaps {
 
             (*v).push(id);
           }
-          Arg(_, _, by_ref) | Arg(_, _, by_val) | Self | Field(_) |
-          ImplicitRet |
+          Arg(_, _, by_ref) | Arg(_, _, by_mutbl_ref) |
+          Arg(_, _, by_val) | Self | Field(_) | ImplicitRet |
           Local(LocalInfo {kind: FromMatch(bind_by_implicit_ref), _}) => {
             debug!("--but it is not owned");
           }
@@ -831,9 +831,9 @@ impl Liveness {
         let mut changed = false;
         do self.indices2(ln, succ_ln) |idx, succ_idx| {
             changed |= copy_if_invalid(copy self.users[succ_idx].reader,
-                                       &mut self.users[idx].reader);
+                                       self.users[idx].reader);
             changed |= copy_if_invalid(copy self.users[succ_idx].writer,
-                                       &mut self.users[idx].writer);
+                                       self.users[idx].writer);
             if self.users[succ_idx].used && !self.users[idx].used {
                 self.users[idx].used = true;
                 changed = true;
@@ -844,10 +844,10 @@ impl Liveness {
                ln.to_str(), self.ln_str(succ_ln), first_merge, changed);
         return changed;
 
-        fn copy_if_invalid(src: LiveNode, dst: &mut LiveNode) -> bool {
+        fn copy_if_invalid(src: LiveNode, &dst: LiveNode) -> bool {
             if src.is_valid() {
                 if !dst.is_valid() {
-                    *dst = src;
+                    dst = src;
                     return true;
                 }
             }
@@ -919,7 +919,7 @@ impl Liveness {
         // inputs passed by & mode should be considered live on exit:
         for decl.inputs.each |arg| {
             match ty::resolved_mode(self.tcx, arg.mode) {
-              by_ref | by_val => {
+              by_mutbl_ref | by_ref | by_val => {
                 // These are "non-owned" modes, so register a read at
                 // the end.  This will prevent us from moving out of
                 // such variables but also prevent us from registering
@@ -1573,7 +1573,7 @@ fn check_expr(expr: @expr, &&self: @Liveness, vt: vt<@Liveness>) {
         let targs = ty::ty_fn_args(ty::expr_ty(self.tcx, f));
         for vec::each2(args, targs) |arg_expr, arg_ty| {
             match ty::resolved_mode(self.tcx, arg_ty.mode) {
-                by_val | by_copy | by_ref => {}
+                by_val | by_copy | by_ref | by_mutbl_ref => {}
                 by_move => {
                     self.check_move_from_expr(*arg_expr, vt);
                 }
@@ -1866,6 +1866,19 @@ impl @Liveness {
         for decl.inputs.each |arg| {
             let var = self.variable(arg.id, arg.ty.span);
             match ty::resolved_mode(self.tcx, arg.mode) {
+              by_mutbl_ref => {
+                // for mutable reference arguments, something like
+                //    x = 1;
+                // is not worth warning about, as it has visible
+                // side effects outside the fn.
+                match self.assigned_on_entry(entry_ln, var) {
+                  Some(_) => { /*ok*/ }
+                  None => {
+                    // but if it is not written, it ought to be used
+                    self.warn_about_unused(sp, entry_ln, var);
+                  }
+                }
+              }
               by_val | by_ref | by_move | by_copy => {
                 self.warn_about_unused(sp, entry_ln, var);
               }
diff --git a/src/rustc/middle/mem_categorization.rs b/src/rustc/middle/mem_categorization.rs
index dc5874ea2cf..fe465db1312 100644
--- a/src/rustc/middle/mem_categorization.rs
+++ b/src/rustc/middle/mem_categorization.rs
@@ -523,6 +523,9 @@ impl &mem_categorization_ctxt {
             // m: mutability of the argument
             // lp: loan path, must be none for aliasable things
             let {m,lp} = match ty::resolved_mode(self.tcx, mode) {
+              ast::by_mutbl_ref => {
+                {m: m_mutbl, lp: None}
+              }
               ast::by_move | ast::by_copy => {
                 {m: m_imm, lp: Some(@lp_arg(vid))}
               }
diff --git a/src/rustc/middle/trans/base.rs b/src/rustc/middle/trans/base.rs
index 368a523306e..ce596586ddc 100644
--- a/src/rustc/middle/trans/base.rs
+++ b/src/rustc/middle/trans/base.rs
@@ -1503,7 +1503,7 @@ fn copy_args_to_allocas(fcx: fn_ctxt,
         // the event it's not truly needed.
         let llarg;
         match ty::resolved_mode(tcx, arg_ty.mode) {
-            ast::by_ref => {
+            ast::by_ref | ast::by_mutbl_ref => {
                 llarg = raw_llarg;
             }
             ast::by_move | ast::by_copy => {
diff --git a/src/rustc/middle/trans/callee.rs b/src/rustc/middle/trans/callee.rs
index c851c5bc725..e7b4dd171e3 100644
--- a/src/rustc/middle/trans/callee.rs
+++ b/src/rustc/middle/trans/callee.rs
@@ -592,7 +592,7 @@ fn trans_arg_expr(bcx: block,
             DoAutorefArg => { val = arg_datum.to_ref_llval(bcx); }
             DontAutorefArg => {
                 match arg_mode {
-                    ast::by_ref => {
+                    ast::by_ref | ast::by_mutbl_ref => {
                         val = arg_datum.to_ref_llval(bcx);
                     }
 
diff --git a/src/rustc/middle/trans/reflect.rs b/src/rustc/middle/trans/reflect.rs
index ef1cc15f5c0..cdd11ee85c5 100644
--- a/src/rustc/middle/trans/reflect.rs
+++ b/src/rustc/middle/trans/reflect.rs
@@ -208,6 +208,7 @@ impl reflector {
                   ast::expl(e) => match e {
                     ast::by_ref => 1u,
                     ast::by_val => 2u,
+                    ast::by_mutbl_ref => 3u,
                     ast::by_move => 4u,
                     ast::by_copy => 5u
                   }
diff --git a/src/rustc/middle/trans/shape.rs b/src/rustc/middle/trans/shape.rs
index e7dfac42bec..cf58b5b51c4 100644
--- a/src/rustc/middle/trans/shape.rs
+++ b/src/rustc/middle/trans/shape.rs
@@ -49,12 +49,12 @@ fn mk_ctxt(llmod: ModuleRef) -> ctxt {
     return {mut next_tag_id: 0u16, pad: 0u16, pad2: 0u32};
 }
 
-fn add_u16(dest: &mut ~[u8], val: u16) {
-    *dest += ~[(val & 0xffu16) as u8, (val >> 8u16) as u8];
+fn add_u16(&dest: ~[u8], val: u16) {
+    dest += ~[(val & 0xffu16) as u8, (val >> 8u16) as u8];
 }
 
-fn add_substr(dest: &mut ~[u8], src: ~[u8]) {
+fn add_substr(&dest: ~[u8], src: ~[u8]) {
     add_u16(dest, vec::len(src) as u16);
-    *dest += src;
+    dest += src;
 }
 
diff --git a/src/rustc/middle/trans/type_use.rs b/src/rustc/middle/trans/type_use.rs
index 9140ea94e9c..6bd3c22f626 100644
--- a/src/rustc/middle/trans/type_use.rs
+++ b/src/rustc/middle/trans/type_use.rs
@@ -53,7 +53,7 @@ fn type_uses_for(ccx: @crate_ctxt, fn_id: def_id, n_tps: uint)
                     by_val | by_move | by_copy => {
                         type_needs(cx, use_repr, arg.ty);
                     }
-                    by_ref => {}
+                    by_ref | by_mutbl_ref => {}
                 }
             }
         }
diff --git a/src/rustc/middle/trans/uniq.rs b/src/rustc/middle/trans/uniq.rs
index 50ea363ace2..6ab91c4a1d7 100644
--- a/src/rustc/middle/trans/uniq.rs
+++ b/src/rustc/middle/trans/uniq.rs
@@ -3,6 +3,7 @@ use lib::llvm::ValueRef;
 use common::*;
 use build::*;
 use base::*;
+use shape::llsize_of;
 use datum::immediate_rvalue;
 
 export make_free_glue, autoderef, duplicate;